The invention relates to a method and apparatus for generating data representing an input profile.
In colour imaging technologies one of the major parts of the process is editing and changing the colours in an image. The changes can be aesthetic, e.g. a particular user may like very green grass or technical, e.g. to correct for a scanner with poor blue response. These user edits have until now been stored in individual company""s proprietary file formats, i.e. a vendor-specific macro file that can only be used within that particular manufacturers environment. There now exists an internationally agreed file format for this user edit information. New colour imaging software will be ICC file format compatible. The proprietary user edit files cannot be used in the new ICC environment. Users will have spent many man-hours empirically/iteratively developing colour edits and will want to be able to retain these under the new ICC based software. Also users may want to switch from their current equipment to a different software or hardware configuration but retain the edits.
The conversion of proprietary user edit files into ICC profiles is not a straightforward task and at present is only carried out by the machine vendors who can convert their own user edit files into the standardised ICC format.
In accordance with one aspect of the present invention, a method of generating data representing an input profile defining a relationship between input colour data generated by an input device and modified in accordance with a predetermined algorithm, and corresponding device independent data comprises:
a) operating the input device on a range of predetermined input colours to generate said input colour data;
b) processing said input colour data in accordance with the predetermined algorithm to generate output data suitable for operating an output device;
c) converting said output data to said device independent data; and,
d) generating said input profile data such that application of said input profile to said input colour data substantially generates said device independent data.
In accordance with a second aspect of the present invention, an image processing system comprises an input device for generating input colour data defining the colour content of pixels of an image; a processor for processing said input colour data in accordance with a predetermined algorithm to generate output data suitable for operating the output device, and for converting said output data to device independent data, and thereby generating input profile data representing an input profile defining a relationship between input colour data generated by the input device and modified according to the predetermined algorithm, and corresponding device independent data.
We also provide a record medium such as ROM, floppy disc, or CD which carries a computer program for carrying out step d) and preferably also step c).
This record medium could be supplied with an input device, an output device or separately.
We have developed a new method and system which enables users themselves to generate the required input profile corresponding to their own xe2x80x9cuser editsxe2x80x9d or xe2x80x9cpredetermined algorithmxe2x80x9d and does not require manufacturer intervention. In this process, the user arranges for a test chart to be scanned by the input device and the method analyses the effect of the predetermined algorithm on the data from the input device, after conversion to device independent data, and so creates a relationship (constituting the input profile) between the input colour data and the device independent data.
The predetermined algorithm may represent modifications needed to compensate for errors in the input device and/or the output device and/or could be used to impart desired colour modifications. These are all techniques which are implemented in conventional user edit files.
Thus, the invention may provide a method and apparatus for converting proprietary image edit files into files compatible with an xe2x80x9copenxe2x80x9d colour management system. The invention is a process to convert vendor-specific edit files into ICC compliant device profiles.
Typically, an output profile will be associated with the output device, that output profile modifying device independent data in a conventional way so as to be suitable for the output device. In that case, step c) preferably comprises applying said output data in reverse to an output profile associated with the output device. The reversed output profile may be constituted by an exact reversal of the output device profile or more usually a reduced resolution version. In that event, it may be necessary to carry out an iterative improvement process as well.
Although the method could be carried out on a range of input colours presented in sequence, preferably step a) is carried out using a test chart which presents the predetermined input colours at corresponding predetermined locations. This simplifies subsequent processing.
The device independent data will typically comprise profile connection space (PCS) data although other device independent colour spaces could be used. For convenience, xe2x80x9cdevice independent colour spacexe2x80x9d will be referred to as PCS although this should not be restricted to the ICC definition of PCS. That ICC definition includes two main units of space data: PCS XYZ and PCS Lab.
Typically, the input colour data and the output data will be defined in different colour spaces, for example red, green, blue (RGB) and cyan, magenta, yellow, black (CYMK) although this is not essential and the predetermined algorithm could convert from one set of RGB values to another set of RGB values, i.e. within the same colour space.